DE
WA2LGN
My QTH is Blue Point, NY, USA, which is approximately 80km east of New York City, on the south shore of Long Island. I live with my lovely wife Kimberly (who puts up with my various hobbies) and our children Harry and Anne. I am Director of Market Intelligence for a multinational corporation, which means I am responsible for keeping track of developments in our industry, as well as looking around the bend for the Next Big Thing. My major career up to this point has been in and around the technical publications field, with stints in sales engineering, marketing, and general management.
I run a Kenwood TS-820 with the matching AT-200 manual antenna tuner. As you can see by the diagram (below), my yard is not large enough for a fabulous antenna system: the trees are all in the wrong places, and "domestic tranquility" issues keep me from erecting anything other than "stealth" antennas. So, I've been experimenting with various antenna designs: my first try was a single-ended Zepp, which had marginal performance. I then went to a modified horizontal Delta Loop, which worked better when I put in an insulator in its electrical center... I dubbed this the "ZeppaLooper" since it was electrically a double Zepp, but physically a delta loop. This antenna was OK until I figured out how to add an additional support - so in December 2003 I put up a 40m horizontal ("Skywire") loop. In the diagram, the dimensions are "paced off" estimates, as one of the Loop Skywire's wonderful features is that the length is not very critical. Since I am running "barefoot" the 300-ohm TV twinlead feedline is entirely satisfactory - it's low loss, inexpensive, and readily available.
My MFJ-269 antenna analyzer puts the loop's fundamental frequency at 7.160mHz, which suggests a length of approximately 142 feet. Loop Skywires like to be higher than mine - but about 18 feet is as high as mine will get. I am experimenting with several drive configurations:
Configuration 1 is what I use most of the time. However, I've had good performance using Configuration 2, and I am not really sure why... so I have been asking a lot of questions, and experimenting... after all, isn't that what this hobby is all about?? Rounding out the list: Configuration 3 works but puts a lot of RF into the shack. Configuration 4 doesn't perform well at all. (I home brewed the balun, using carefully researched materials and plans... since it STILL doesn't work well, I blame my workmanship!!)
In operation, the 40m loop is proving quieter than the previous Zeppalooper, and far quieter than the 10m vertical I recently added. On 40, 80, and 160m the loop emits a Near Vertical Incidence Skywave (NVIS) which provides reliable communications within about a 500 mile radius, almost regardless of band conditions. On the higher bands, the theoretical takeoff angle is lower and it's a nice DX performer (I worked ZS6WRL on 15 meters on 10 January 2004, which is almost 8,000 miles from my little corner of the basement!)
QRP performance is also astounding with the Skywire Loop antenna. On 40m CW on 2 July 2005, I worked Mauro (I1MMR) in Genoa, Italy using 5 watts of output power: a distance of 4003 miles! I am on QRP lately due to some RFI issues; my signal swamps the cheap white noise machine we use in our daughter's room to help lull her to sleep. (One day either I'll get around to fixing the problem (Ferrite beads?) or she'll sleep through the night without a noise machine in her room.)
I've been bitten by the glow bug recently. I've built a few good receivers (and a few bad receivers), and I am tinkering with a construction project - a 6SJ7/6L6 CW transmitter. This started out as a MOPA (Master Oscillator Power Amplifier) with just the 6L6; I've added a separate oscillator stage, so now I can call it a "DOPA". Partly because of the Skywire Loop's great efficiency as a QRP antenna, I don't need a lot of power to get out on 40M - so if you hear a chirpy signal around 7040KHz, it's probably just me.
Here's a diagram of the current antenna configuration:
1. Drive one leg of the feedline from the random wire output with the other leg grounded,
2. Drive one leg of the feedline from the random wire output, with the other leg floating (unconnected),
3. Drive both legs of the feedline from the random wire output (using a shorting jumper),
4. Drive the feedline through a 4:1 balun.
Please email me any comments on this antenna system, or just to say hello!
Rick Andersen's Cool Radio Projects page
I've spent many an hour tinkering with the 40m regen receiver that Rick (KE3IJ) was kind enough to publish... and Rick himself has taken the time to patiently answer my questions and make improvement suggestions. Cool stuff, great guy. And he's a ham with a horizontal loop!
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